1. Field of the Invention
The present invention relates to a perforating device or similar means especially adapted for use with printing machines such as those of the offset variety as well as the method of operation on said device.
2. Description of the Prior Art
In a general way, a common type of known perforating device used with printing machines consists of a strip, generally metallic, presenting a lateral toothed or sharp raised edge having upon its face opposite the teeth, a layer of adhesive material upon which a protective tape is set which is removed at the moment of use.
A perforating device of this construction is intended to be applied to a pressure cylinder of the printing machine and, more particularly, in the case of an offset machine, on the feeder cylinder pressing the sheets to be printed on the blanket cylinder.
The positioning of the perforating device is then carried out in the following manner:
First, the pressure cylinder is cleaned so as to permit good adhesion of the perforating device thereto.
Next, the text to be printed is transferred upon the pressure cylinder in order to have a guide mark for the proper positioning of the perforating device.
After cutting the perforating device to the length required, the protective tape is removed and the device is adhesively applied to the pressure cylinder at the desired position.
Next, printing trial runs are carried out to determined whether the perforating device is properly positioned and thereafter the final printings are carried out. Of course, in the case where the perforator is not in proper position, whether for having moved during manipulation or else by reason of an error in the positioning operation, the aforedescribed steps must be at least partially repeated.
This procedure is subject to a number of drawbacks:
It is not practical for all printing machines, particularly those in which the pressing or feeding roller is not readily accessible.
Its operation is particularly delicate and is carried out only with difficulty. Thus, the operator must often contort his body in order to succeed in applying the perforating device to the presser roller.
It necessitates a relatively long period of time for being put in operation which is the cause of frequent and prolonged stopping of the printing machine thereby reducing the profit-making capability of the machine and increasing the cost of printed matter.